See Jupiter take one for the solar system

On March 17 the gas giant planet was pummeled by a speeding space rock, and backyard skywatchers happened to capture the cosmic violence at the moment of impact.

The sighting is the latest in a rash of impacts seen on Jupiter: Amateur astronomers caught similar events in 2009, 2010, and 2012. Before the recent onslaught, it was thought that Jupiter impacts were rare, with the 1994 smashup of comet Shoemaker-Levy 9 being a spectacular exception.

But the latest thinking is that Jupiter may be a shield for Earth, sucking in space rocks before they can reach us—or it may act as a slingshot, eating up a few impacts but also sending comets and asteroids our way, possibly including the ones that may have delivered the ingredients for life to our home world.

By chance, two amateur astronomers in Austria and Ireland independently caught the latest collision on video, only discovering the event this week after going through their footage. In the film, the impact appears as a pinprick flash of light on the edge of the planet’s round face.

Amateur astronomer Gerrit Kernbauer caught this footage of a space rock hitting Jupiter on March 17.

It’s unclear whether the impactor was a wayward meteor or comet sucked in by the huge planet’s gravitational pull. Whatever it was, astronomer Phil Plait writes that based on the visible size of the explosion, he estimates the object may have been no more than a few tens of meters wide.

Big guns like the Hubble Space Telescope could be enlisted to investigate further if astronomers find a dark stain left behind on Jupiter’s cloud tops—a sign of soot produced as the atmosphere superheated during the explosion. So far, though, no such remnant has been reported.

Impact Shield, or Source?While astronomers have begun to think that Jovian impacts are fairly common, questions remain about the popular theory that Jupiter is Earth’s protector, sweeping up potentially hazardous asteroids and comets before they can reach us.

A new study released last month in the journal Astrobiology even suggests that the opposite may be happening. Computer models have shown that while Jupiter may swallow some objects in concert with Saturn, the two gas giants also can kick errant comets and asteroids into the inner solar system, sending some to cross Earth’s orbit.

John McKeon in Ireland also caught a view of a bright object near the surface of Jupiter.

At the same time, simulations also show that organic compounds important to the development of life could have been delivered to Earth billions of years ago via the space rocks sent our way by the two giant planets.

Catching sight of these kinds of impacts requires a large backyard telescope equipped with a digital camera, not to mention a lot of luck. But spotting Jupiter in the sky with the naked eye is easy. The gas giant is visible as a bright, creamy-colored star even from heavily light-polluted cities.

On the next clear night, you can find the largest planet in the solar system rising in the east after sunset. As the night progresses, the super-bright planet will continue to glide across the southern sky in the overnight hours and set in the west at dawn. Train even a small telescope on the planet, and you can glimpse the distinctive cloud belts across its equatorial region, with the four largest moons lined up along side it, reports national-geographic.com.